Book Description
This digital document is an article from Journal of the Air & Waste Management Association, published by Thomson Gale on March 1, 2007. The length of the article is 6491 words. The page length shown above is based on a typical 300-word page. The article is delivered in HTML format and is available in your Amazon.com Digital Locker immediately after purchase. You can view it with any web browser.

Citation Details
Title: Modeling dispersion from toxic gas released after a train collision in Graniteville, SC.(TECHNICAL PAPER)
Author: Robert L. Buckley
Publication: Journal of the Air & Waste Management Association (Magazine/Journal)
Date: March 1, 2007
Publisher: Thomson Gale
Volume: 57Issue: 3Page: 268(11)

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Book Description
This digital document is a journal article from Environment International, published by Elsevier in 2006. The article is delivered in HTML format and is available in your Amazon.com Media Library immediately after purchase. You can view it with any web browser.

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This analysis seeks to evaluate the influence of emission source location on population exposure in China to fine particles and sulfur dioxide. We use the concept of intake fraction, defined as the fraction of material or its precursor released from a source that is eventually inhaled or ingested by a population. We select 29 power-plant sites throughout China and estimate annual average intake fractions at each site, using identical source characteristics to isolate the influence of geographic location. In addition, we develop regression models to interpret the intake fraction values and allow for extrapolation to other sites. To model the concentration increase due to emissions from selected power plants, we used a detailed long-range atmospheric dispersion model, CALPUFF. Primary fine particles have the highest average intake fraction (1x10^-^5), followed by sulfur dioxide (5x10^-^6), sulfate from sulfur dioxide (4x10^-^6), and nitrate from nitrogen oxides (4x10^-^6). For all pollutants, the intake fractions span approximately an order of magnitude across sites. In the regression analysis, the independent variables are meteorological proxies (such as climate region and precipitation) and population at various distances from the source. We find that population terms can explain a substantial percentage of variability in the intake fraction for all pollutants (R^2 between 0.86 and 0.95 across pollutants), with a significant modifying influence of meteorological regime. Near-source population is more important for primary coarse particles while population at medium to long distance is more important for primary fine particles and secondary particles. A significant portion of intake fraction (especially for secondary particles and primary fine particles) occurs beyond 500 km of the source, emphasizing the need for detailed long-range dispersion modeling. These findings demonstrate that intake fractions for power plants in China can be estimated with reasonable precision and summarized using simple regression models. The results should be useful for informing future decisions about power-plant locations and controls. ... Read more

Book Description
This digital document is a journal article from Atmospheric Environment, published by Elsevier in 2005. The article is delivered in HTML format and is available in your Amazon.com Media Library immediately after purchase. You can view it with any web browser.

Description:
Hourly mean concentration data for nitrogen oxides (NO"X), nitrogen dioxide (NO"2) and ozone (O"3) have been used to derive a method for estimating the mean primary NO"2 fraction from vehicle exhausts in London. A set of simple chemical equations has been used to explain the differences in NO"2 concentrations between background and roadside site pairs and to estimate the proportion of NO"2 that is likely to be derived from primary NO"2 vehicle emissions and the NO"2 formed through the reaction of nitric oxide (NO) with O"3. These results suggest that there is a wide range of primary NO"2 emission fractions observed on different roads in London. The estimates ranged from 3.2 to 23.5 vol% with a median value of 10.6 vol% for the 43 measurement sites considered. A median primary NO"2 fraction of 10.6% accounts for an average of 21% of the observed NO"2 concentration at roadside sites. The range in calculated primary NO"2 fractions explains much of the variation in annual mean NO"2 concentrations between monitoring sites in London. The estimated primary NO"2 fraction is considerably higher than the 5.0 vol% typically used in modelling studies that aim to predict ambient NO"2 concentrations. These results have implications for the assessment of NO"2 concentrations in London and whether London will meet the limit values set by the European Union. Further work is required to explain the wide range of primary NO"2 fractions estimated in terms of road traffic composition and activity. ... Read more

Book Description
This digital document is a journal article from Atmospheric Environment, published by Elsevier in . The article is delivered in HTML format and is available in your Amazon.com Media Library immediately after purchase. You can view it with any web browser.

Description:
A semi-analytical Lagrangian particle model to simulate the pollutant dispersion during low wind speed conditions is presented and tested. The method relies to a stochastic integral equation whose solution is obtained using ILS method, which consists in the iterative solution of Langevin equation by the Picard's iteration method. To consider the low wind speed effect, the solution for the horizontal components of the turbulent velocity takes account the Eulerian autocorrelation function as suggested by Frenkiel [1953. Advances in Applied Mechanics 3, 61-107]. The model results are shown to agree very well with the field tracer data collected during stable conditions at Idaho National Engineering Laboratory (INEL) and during convective conditions from the series of field experiments at Indian Institute of Technology (IIT). A statistical analysis reveals that the model simulates very well the experimental data and presents results comparable or even better than ones obtained with other models used as comparison. The analytical feature of the ILS method and the inclusion of the Eulerian autocorrelation function suggested by Frenkiel (1953) allow generating more accurate results. ... Read more

Book Description
This digital document is a journal article from Atmospheric Environment, published by Elsevier in 2004. The article is delivered in HTML format and is available in your Amazon.com Media Library immediately after purchase. You can view it with any web browser.

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During the BERLIOZ field campaign unusually high levels of ozone (88ppbv) and PAN (2.5ppbv) were detected at the Frohnau Tower just north of Berlin, Germany, in the night from 6 to 7 August 1998. In these air masses the formation of PAN was in particular favored compared to ozone due to the enhanced levels of hydrocarbons. Analyses with the particle dispersion model FLEXPART revealed that the pollution had its origin in the Netherlands and the southern United Kingdom about two days before. This event confirms previous findings that regional air quality can substantially be affected by pollution transport from remote regions and that pollution transport should be accounted for in regional air quality standards. ... Read more

Book Description
This digital document is a journal article from Journal of Hazardous Materials, published by Elsevier in 2005. The article is delivered in HTML format and is available in your Amazon.com Media Library immediately after purchase. You can view it with any web browser.

Description:
A probability density function (PDF) fumigation model is presented here to study the dispersion of air pollutants emitted from a tall stack on the shoreline. This work considers dispersion of the pollutants in the stable layer and within the thermal internal boundary layer (TIBL) proceeds independently. The growth of TIBL is considered parabolic with distance inland. Turbulence is taken as homogeneous and stationary. Dispersion of particles (contaminant) in lateral and vertical directions is assumed independent of each other. This assumption allows us to consider the position of particles in both directions as independent random variables. The lateral dispersion distribution within the TIBL is considered as Gaussian and independent of height. A skewed bi-Gaussian vertical velocity PDF is used to account for the physics of dispersion due to different characteristics of updrafts and downdrafts within the TIBL. We have used Weil (J.C. Weil, A diagnosis of the asymmetry in top-down and bottom-up diffusion using a Lagrangian stochastic model, J. Atmos. Sci., 47 (1990) 501-515) solutions to find out the parameters of this PDF. Incorporating finite Lagrangian integral time scale for the vertical velocity component, it is observed that it reduces the vertical dispersion in the beginning and moves the point of maximum concentration further downwind. Due to little dispersion in the beginning, there is more plume to be dispersed causing higher concentrations at large distances. The model has considered Weil and Brower's (J.C. Weil, P.R. Brower, Estimating convective boundary layer parameters for diffusion applications, Maryland Power Plant Siting Program Rep. PPSP-MP-48, Department of Natural Resources, Annapolis, MD, 1985, 37 pp.) convective limit to analyze dispersion characteristics within TIBL. The revised model discussed here is evaluated with the data available from the Nanticoke field experiment on fumigation conducted in summer of 1978 in Ontario, Canada. The results of revised model are in good agreement with the observed data. ... Read more

Book Description
This digital document is a journal article from Atmospheric Environment, published by Elsevier in 2006. The article is delivered in HTML format and is available in your Amazon.com Media Library immediately after purchase. You can view it with any web browser.

Description:
In this work, we present an analytical solution for the nonstationary two-dimensional advection-diffusion equation to simulate the pollutant dispersion in the planetary boundary layer. In this method the advection-diffusion equation is solved by the application of the Laplace transform technique and the solution of the resulting stationary problem by the generalised integral Laplace transform technique (GILTT). We also report numerical simulations and statistical comparison with experimental data available in the literature. ... Read more